Two studies were conducted to develop and validate a work-specific measure of cognitive failure, the Workplace cognitive failure scale (WCFS). In initial item development, content validity was gained via sorting. In Study 1, data were obtained from an employee sample that supported the factorial, construct, and criterion-related validity of the WCFS. In particular, results supported the expected relationships of workplace cognitive failure with facets of personality, role overload, components of self-regulation, and self-reported measures of safety outcomes. Study 2 examined the WCFS in two additional employee samples, and provided further criterion-related validity using objective measures of injury and supervisor ratings of safety behaviour. Overall, results supported the validity and utility of the new measure in assessing organizational safety behaviour and outcomes, more so than the general cognitive failure scale.